Nowadays, instantaneous measurements of moving objects, vehicles in particulars, have become common place technology. Widely known and used in the current technology for geographical position measurement is the GPS satellite measurement technique. These techniques have become the work horse for all kinds of applications, where a precise measurement of a vehicle position is necessary. E.g. for calculating a position on a map, calculating driving directions, calculating distances travelled etc.
However, GPS techniques suffer from various drawbacks that makes them vulnerable for malfunction and misuses. Absence of secure positioning will be a game stopper for cooperative applications that depend upon the users' (absolute) location and traces. Such applications may be financial applications, that tax travelling, in particular, in time and geographical zones.
To save money consumers might spoof/mislead the GPS sensor. On the other hand, safety applications cannot rely on an insecure GPS sensor, where the reliability of reception is always a challenge, especially for difficult terrains, such as urban areas and tunnels.
It is an objective to provide an alternative on GPS based locations, that uses fixed landmarks of known geographical positions. WO 20120154117 provides such a system, that tracks road side based delineator posts by radar reflection. However, this system relies on visibility of a tag that provides the position information, which may be difficult in practical circumstances e.g. when pollution or wear reduces the visibility. Also, the system has to know in advance that a certain radar reflective object needs to be scanned for visible inspection, which may be confusing with many reflective objections in the area.
JP2006275904 teaches a system of passive lane markers buried in the road that are registered in an annexed road side unit. The lane markers are only detected when passed by a vehicle.
US2011/0238306 is another prior art that relies on line of sight detection with other remote vehicles or objects, for example road side units. However, determination of a line of sight signal is done by comparing multipath signals or using a rule scheme for selecting preferred sources. In practice this calls for solutions where further reliability of the detection of a vehicle's location is desired.